There is already known, in particular from Japanese patent application 2000-317797, French patent application 2 834 662, to which US patent application 20050101235 corresponds, and French patent application 2 857 610, to which US patent application 2006/0154581 corresponds, a tool for surfacing an optical surface including: a rigid support having a transverse end surface; an elastically compressible interface attached to the rigid support and having a first transverse end surface, a second transverse end surface and a lateral surface extending from the periphery of the first end surface to the periphery of the second end surface, said first end surface of the interface being pressed against and covering said end surface of the rigid support; and a flexible pad adapted to be pressed against a surface to be worked and that is pressed against and covers at least in part the second end surface of the interface on the opposite side to and in line with said end surface of the rigid support.
To reduce the roughness of the optical surface, the tool is brought into contact with it, applying sufficient pressure to it so that, by deformation of the interface, the pad espouses the shape of the optical surface.
While spraying the optical surface with a fluid, it is driven in rotation relative to the tool (or vice-versa) and swept by the tool.
The optical surface is generally driven in rotation, its rubbing against the tool being sufficient to entrain the tool conjointly in rotation.
The surfacing operation necessitates an abrasive, which can be contained in the pad or in the fluid.
During surfacing, the elastically compressible interface compensates the curvature difference between the end surface of the support of the tool and the optical surface.
The results achieved by such tools are generally satisfactory, but it is sometimes difficult to avoid certain appearance defects, in particular an orange skin effect and a sheeplike effect.
To eliminate these appearance defects, it has already been proposed that the flexible pad should have a diameter greater than the diameter of the interface so that the pad has an annular portion projecting transversely beyond the interface.
Such tools achieve improved appearance of the surface, but in some circumstances such appearance defects can remain.